Reconstructing callable references when using deepcopy over a SM.

fgmacedo commented 5 months ago

Fixes #424.

Issue

As declared on the related issue:

The MachineMixin for Django seems to behave differently when models are used within django tests. Oddly enough, any objects created during setUpTestData seem to cause transitions to bypass checks like conditions.

The root cause of the issue lies in the setUpTestData() method. Every cls attr created in this method is wrapped in a TestData class, which performs a deepcopy() for each test, so this is designed to allow safe alteration of objects between tests on the same TestCase instance.

However, this conflicts with the creation strategy of state machines. The references of properties/methods used as actions/conditions are computed at the time of creation. So, when the state machine is cloned, the references still point to the original instance.

Fix

We've added a hook on the deepcopy Python protocol, where we reconstruct the new instance callable references.

Tests

[x] Test with simple deep copy.
[ ] Test with observers added to the state machine.

codecov[bot] commented 5 months ago

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (f236cad) to head (24f8254).

Additional details and impacted files

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